It is possible to provide new developments in science and technology and to produce solutions to existing problems through education. In this sense, education should reveal a new representation. In this demonstration, the context that students will establish with real life is very important. In this study, it is aimed to determine the effect of REACT, one of the context-based learning strategies in 8th grade electrical loads and electrical energy unit, on students' 21st century skills and self-efficacy beliefs towards learning science. In this study, the effects of REACT strategy, which is an application area of context-based learning, in the development of self-efficacy beliefs and 21st century skills in science learning were determined in this study. The study group consists of 37 8th grade students. The 21st century skills scale and the self-efficacy belief scale for learning science were used as data collection tools. In the experimental group, activities in accordance with REACT strategy were applied. Courses were conducted with the control group students within the framework of the 2018 science curriculum. SPSS package program was used for data analysis. As a result of the research, it was found that there was no significant difference in pre-tests of experimental and control groups and in post-tests a significant difference was found in favor of experimental group in 21st century skills and self-efficacy beliefs towards science.